Sign up during your Initial Enrollment Period or face a permanent penalty

You sign up for Medicare Part B during a seven-month window called your Initial Enrollment Period (IEP). This period runs three months before the month you turn 65, the month you turn 65, and three months after. If you miss this window, you can still enroll later, but you will pay a higher premium for as long as you have Part B — typically 10 percent more for each full year you delayed.

The penalty is permanent. It does not go away after a few years. This means signing up late costs you money every single month for the rest of your life, so the enrollment dates matter more than most Medicare important date.

There are a few situations where you can sign up outside your IEP without penalty. If you or your spouse worked past 65 and had health coverage through that job, you get a special enrollment period after that coverage ends. If you are not yet a U.S. citizen or permanent resident, your IEP may start later. These exceptions are narrow, and the burden is on you to prove you may have access to for one.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after.
  • If you miss your IEP and do not have a may have access to reason, you will pay a permanent 10 percent monthly premium increase for each year you delayed.
  • You can sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • If you had employer health coverage past age 65, you may have a special enrollment period after that coverage ends, which lets you enroll without penalty.
  • Part B covers doctor visits, outpatient care, and some preventive services, and enrollment is separate from Part A (hospital insurance).

How to find your exact enrollment window

Your Initial Enrollment Period depends on your birth month. If you were born on the 15th or later in any month, Medicare counts that as the next month for enrollment purposes. So if you were born on January 20, Medicare treats your birth month as February.

Once you know your birth month, count backward three months for when your IEP starts and forward three months from your birth month for when it ends. For example, if you turn 65 in June, your IEP runs from March through September. You can enroll any time during those seven months.

Social Security will send you a notice in the mail about three months before you turn 65. This notice tells you your specific enrollment dates. If you do not receive it, call Social Security at 1-800-772-1213 to confirm your dates. Do not assume you know them — mail gets lost, and the cost of guessing wrong is high.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your IEP and you do not have a may have access to exception, you enter what Medicare calls a General Enrollment Period. This runs January 1 through March 31 each year. You can enroll then, but your coverage does not start until July 1 of that year — a gap of up to six months with no Part B coverage.

During that gap, you are responsible for any doctor bills. Part B covers 80 percent of approved charges after you meet your deductible, so without it you pay the full cost. That can add up quickly if you need ongoing care.

The permanent premium penalty applies on top of the standard Part B premium. As of 2024, the standard Part B premium is around $165 per month, but this changes yearly. A 10 percent penalty for one year of delay means you pay roughly $16.50 extra per month forever. For five years of delay, that is roughly $82.50 extra per month for life.

Exceptions that let you enroll late without penalty

If you had group health coverage through your own job or your spouse's job after you turned 65, you do not have to sign up for Part B right at 65. You get a special enrollment period that lasts for two months after that coverage ends, with no penalty.

This is the most common exception. Many people work past 65 and keep their employer health plan. As long as you enroll within two months of losing that coverage, you avoid the penalty. You will need to show proof of the coverage — usually a letter from your employer or insurance company stating when it ended.

Other narrow exceptions exist: if you are not yet a U.S. citizen or permanent resident, your IEP may start later. If you were in the Peace Corps or certain other federal programs, different rules may explore. If you think you have a reason to enroll outside your IEP, call Medicare at 1-800-MEDICARE and ask whether you may have access to for a special enrollment period. They can tell you in one call whether your situation is covered.

How to sign up for Part B

You can enroll through three routes: online at Medicare.gov, by phone, or in person. Online is fastest if you are comfortable with it. Go to Medicare.gov, sign in with your username and password, and look for the enrollment option. The site walks you through the steps.

By phone, call 1-800-MEDICARE (1-800-633-4227). Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time. Have your Social Security number and Medicare card (or notice from Social Security) ready. They will ask whether you want Part B and confirm your contact information.

In person, visit your local Social Security office. You can find the nearest one at ssa.gov or by calling 1-800-772-1213. Bring your Social Security card and proof of citizenship or permanent residency. This route takes longer but may help if you have questions about your specific situation.

Part B coverage and what it includes

Part B is optional — you do not have to take it. But if you do not, you pay out of pocket for doctor visits, outpatient surgery, diagnostic tests, and most preventive care. Part B covers 80 percent of the approved amount after you meet your annual deductible (which changes yearly).

Part B does not cover everything. It does not pay for dental, vision, hearing aids, or long-term care. Many people add a Medigap or Medicare Advantage plan to cover gaps. Medigap is supplemental insurance sold by private companies. Medicare Advantage is an alternative to Original Medicare that often includes dental and vision but usually requires you to use specific doctors.

You can enroll in Part B, Medigap, and Medicare Advantage at different times, but the rules about when you can switch are strict. If you enroll in Part B late, you may lose the chance to buy certain Medigap plans without medical underwriting. This is another reason to enroll on time — it keeps your options open.

Frequently Asked Questions

What if I turn 65 but am not ready to retire?

You still need to decide about Part B. If you have health coverage through your job, you can delay Part B without penalty as long as that coverage continues. Once your job coverage ends, you have two months to enroll in Part B. If you miss that window, the permanent penalty applies.

Can I sign up for Part B before I turn 65?

Yes. You can enroll starting three months before your birth month. Many people sign up early to make sure coverage starts on time. There is no downside to enrolling early — your coverage will not start until the first day of the month you turn 65 or the month after, depending on when you enroll.

Do I have to take Part A and Part B at the same time?

No. Part A (hospital insurance) and Part B (medical insurance) are separate. Most people are automatically enrolled in Part A at 65 if they have worked long enough. You can refuse Part A, but you must actively choose whether to take Part B. The enrollment important date are the same, but the decisions are independent.

What if I miss the important date by a few days?

Medicare counts enrollment by the month, not the day. If your IEP ends in September, you can enroll any time in September and your coverage will start October 1. If you enroll in October, you have missed your IEP and the penalty rules explore. Call Medicare when ready if you think you are close to a important date — they can confirm the exact date.

Will my premium go down if I wait to enroll?

No. Part B premiums are set by Medicare and do not vary based on when you enroll. The only financial consequence of late enrollment is the permanent penalty. There is no savings from waiting.